1. Field of the Invention
This invention relates to monitoring damper position. More particularly, this invention relates to monitoring and calibrating damper position of a damper in a heating system.
2. Description of the Prior Art
In a heating system, fuel and combustion air are generally provided to a combustion chamber where they are ignited and burned. Fuel and air supplies are controlled by a modulation motor which rotates air damper and fuel valve shafts between a closed position (a low fire position) and an open position (a high fire position). Modulation of the rate that an air and fuel mixture is supplied to the combustion chamber (the firing rate) is accomplished by operating the air damper and fuel valve shafts between the low fire and high fire positions.
In the past, the firing rate has been controlled by crude, electromechanical devices. High fire and low fire position information was provided to a heating system controller by limit switches which were activated by cams mounted on the modulation motor shaft. However, the cams were mounted on the motor shaft at operating angles which were adjustable and could, therefore, be misadjusted. A misadjusted operating angle could lead to a false indication of a high fire or low fire position to the heating system controller. This, in turn, could lead to insufficient purging of the combustion chamber at start-up or to ignition at a high gas flow-rate. Both of these situations are undesirable. In addition to safety concerns, position accuracy is poor in this type of damper control.
Therefore, there is a need for a damper control system which is both safe and which maintains position accuracy.